In 1964, he was chosen to be the life support physician for phase two of the Man in Sea project sponsored by the National Geographic Society and Smithsonian Institution.
In 1965, he directed over 75 experimental dives for OceanSystems, then the world’s largest commercial diving company.
In 1967 became a consultant to the USNavy’s Sealab project.
In 1968, he was certified by the US Navy as a Man-In-Sea Aquanaut for its Sealab III program.
In 1969, he constructed Sublimnos, Canada’s first subsurface research laboratory, the only freshwater underwater lab, the only under-ice station and it was the only free submerged habitat in the world.
He wrote Canada’s first national ocean policy.
Supported by the Canadian Government, he conducted a series of ten research expeditions to study techniques for working under the Arctic Ocean.
He founded the James Allister MacInnis Foundation for underwater research education in Canada.
In 1972, he led a team that constructed the first manned underwater station Sub Igloo in the Arctic Ocean.
He was the first person to explore the freezing waters under the North Pole and by the mid-1970’s, had been on more than 100 expeditions and major dives around the world.
In 1976, he became a member of the Order of Canada, his nation’s highest honor, for his pioneering research on undersea science and engineering projects.
n 1975, he discovered a fragment of the world’s northernmost-known shipwreck, the HMS Breadalbane. In 1978, he headed a five-man crew for the first expedition to find the whole wreck of the ship.
In 1985 when he was an adviser to the team that discovered the wreck of the RMS Titanic.
In 1987, aboard the French submersible Nautile, he made his first nine-hour dive to the Titanic at 4,000m south of Newfoundland.
In 1991, he was the co-leader of a $5 million expedition to film Titanic on the giant-screen IMAX format. It was his expedition that inspired Canadian filmmaker James Cameron’s Academy Award winning film, which hit the big screens in 1997.
In 2003, MacInnis accompanied Cameron on the Disney-IMAX expedition to the Atlantic and Pacific Oceans, which resulted in the 3-D film, Aliens of the Deep.
In 2005, MacInnis teamed with Cameron for the Discovery Channel expedition which broadcast live images of the last remaining unseen rooms of the Titanic. The expedition involved the world’s largest research ship, 130 people, two $2 million subs and five mini-robots.
In 2012, he was expedition physician and journalist for Cameron and National Geographic for the seven-mile deep solo science dive into the Mariana Trench in the western Pacific Ocean, the deepest natural trench in the world.
Creator of the WOWSA Awards, World Open Water Swimming Association, the Daily News of Open Water Swimming, Oceans Seven, Open Water Summit, Openwaterpedia, KAATSU Global and KAATSU Research Institute. Inductee in the International Marathon Swimming Hall of Fame, recipient of the Poseidon Award and Irving Davids-Captain Roger Wheeler Memorial Award of the International Swimming Hall of Fame, and a member of the Ice Swimming Hall of Fame, and former FINA Technical Open Water Swimming Committee member, Technical Delegate with the 2011 Special Olympics World Summer Games, and 9-time USA Swimming coaching staff.